Tuesday, September 13, 2011

How To Fix SSH On A Cisco ASA When It Quits Working

I went to a customer site today, and one of the complaints that they had was that they could no longer SSH into their ASAs.  So, with that said, I told them I would fix this.  Now, I specifically remember SSH'ing into these ASAs before, without issue.  So, Im not sure what has happened.  Now, I know that a few days back, we replaced the primary ASA (in this Active/Standby configuration).  I suspect that ASA lost its key when we put the new primary ASA in and it sync'ed with the secondary ASA (it pulled FROM the secondary, to be clear).  So, as I began to troubleshoot this, here is what fixed the issue:
"crypto key generate rsa modulus 2048"
I typed this in and it resolved my SSH issue.  I am not 100% sure if the reason I gave above is correct, but I do suspect this to be the case, since I know only a few days ago I made this change.  Follow that story at this link: